Thermal wheel

ABSTRACT

A rotary thermal wheel assembly for heat transfer, mass transfer or a combination of heat and mass transfer has a hub, a number of rigid spokes which are connectable to the hub, and a heat and/or mass transferring media pack. The media pack is arranged in the space defined by the hub and the spokes. The hub is a tubular element provided with connection means, and the spokes are connectable to the hub by connection parts which match the correspondingly shaped connection means of the hub.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national stage application of and claimspriority to International Patent Application No. PCT/EP15/063220 filedJun. 12, 2015, which claims priority to Sweden Patent Application No.1450736-2 filed Jun. 13, 2014, both of which are hereby incorporated byreference in their entirety.

TECHNICAL FIELD

The present disclosure relates to heat transfer, mass transfer or acombination of heat and mass transfer, and more specifically to rotarythermal wheels of this kind provided with a support structure. Thedisclosure also concerns a method for assembling the thermal wheel.

BACKGROUND

Rotary wheels for heat and/or mass transfer are used for exchanging heatand/or mass between air flows, e.g. for regaining heat of outlet air andproviding inlet air of domestic ventilation systems with such heat. Arotary wheel for heat and/or mass transfer is referred to as “thermalwheel” which is arranged such that one portion of the wheel is incontact with the outlet air and one with the inlet air. During use, thethermal wheel will rotate, such that a portion thereof having assumedthe temperature of the outlet air at a subsequent stage will be incontact with the inlet air, such that the heat absorbed by the thermalwheel from the outlet air will heat the inlet air. By using a rotarywheel for heat and/or mass transfer, the thermal losses due toventilation may be reduced significantly.

A “thermal wheel” usually comprises a hub assembly for fastening thethermal wheel to a rotary shaft.

WO2010/144032 discloses a rotor of a rotating heat exchanger having atleast two sections and being provided with at least one peripheralelement, at least one radial element and clamping means for fasteningthe at least two sections. Each clamping mean is connected to a radialelement and to a peripheral element and it applies tension to the radialand peripheral elements when it is tightened.

A known technique used to fasten spokes to a hub is welding. This causesa poor working environment, due to produced welding gases. Welding ofaluminum may result in crack formation, which may have negative impacton the shape of the wheel as a consequence; it will not be absolutelycircular, which in turn affects the efficiency and the durability of thefinished wheel. A more rational production may be accomplished withoutwelding.

In U.S. Pat. No. 4,234,038A a rotating transfer wheel assembly isdescribed which comprises a hub with a number of radial blades connectedthereto. A condition transfer medium is arranged in the space betweenthe blades. The blades extend between sections of the transfer mediumand are secured to the hub by screws, which is both cumbersome and timeconsuming.

U.S. Pat. No. 4,924,934A describes a heat transfer wheel comprising ahub, a number of spokes extending between the hub and a peripheral band.Wedge shaped elements are provided between the spokes. The spokes areattached to the hub and the band by means of hooks which are connectedto ridges of the hub. This fastening method requires that the spokes areflexible, which in turn requires certain means in order to provide thewheel with stability.

In U.S. Pat. No. 2,680,492A a heat transfer wheel is shown whichcomprises two hubs and a number of rods extending radially from the hubto an annular band is described. These rods are attached to the hub bymeans of threads.

A further heat transfer wheel is disclosed in U.S. Pat. No. 4,191,241Awhich comprises a hub, a heat transfer medium, a peripheral elementextending around the wheel and arms extending radially between the huband the peripheral element. These arms are welded to the structure.There are, as mentioned above, several disadvantages with a weldedwheel.

Further background art is disclosed in EP2375211A2 and U.S. Pat. No.6,422,299B1.

From the above it is understood that there is room for improvements.

SUMMARY

An object of the present disclosure is to provide a new type of thermalwheel which is improved over prior art and which eliminates or at leastmitigates the drawbacks discussed above. This object is obtained by athermal wheel having the features of appended claim 1 with preferredembodiments set forth in the dependent claims related thereto.

In a first aspect of the disclosure a rotary thermal wheel for heatand/or mass transfer is provided. The rotary thermal wheel comprises ahub, a number of radial spokes which are connected to the hub, and aheat and/or mass transferring media pack. The media pack is provided ina space defined by the hub and the spokes. Further, the hub comprises atubular element provided with connection means. The spokes are connectedto the hub by means of connection parts which match the correspondinglyshaped connection means. The connection of the spokes is a complementaryshaped connection. This thermal wheel is advantageous since the assemblyis facilitated due to the complementary shaped connection between thehub and the spokes.

The connection means may comprise recesses formed on the inside of thehub. This is advantageous since the outer surface of the hub is kepteven.

In one embodiment, the connection means are substantially rectangularshaped connection recesses. The advantage of the rectangular connectionmeans are that they match correspondingly shaped connection parts.

Preferably, the rectangular connection means comprise wall elementswhich provide grooves. The spokes are attachable to the hub by means ofconnection parts fastened to one end of the spoke and inserted into therectangular connection means of the hub. The advantage of the groove isthat a matching part, e.g. a connection part fastened to a spoke, can beinserted into it. This is an efficient assembly method which does notinclude any harmful gases, like for instance welding does. Anotherdisadvantage regarding welding is that it causes adverse effects on thewheel such as shape changes or cracks.

The connection means may be equidistantly arranged around the inside ofthe hub. It provides better stability to the wheel if the spokes areequidistantly arranged around the wheel.

In one embodiment, the thermal wheel comprises a peripheral member whichextends around the outer periphery of the thermal wheel. The peripheralmember is connected to the spokes by fastening means. The peripheralmember encloses the media pack. An advantage with a thermal wheelequipped with a peripheral member is that a winded media pack is held inplace and cannot unwind so easily.

Preferably, the spokes extends radially from the hub to the peripheralmember. This is an efficient way to fasten the spoke, but it would alsobe possible to have a shorter spoke and transversal struts extendingstraight through the media pack at some distance between the hub and thelast winding of the media pack. The transverse strut would be connectedto the spokes at either side of the media pack.

In one embodiment, the peripheral member extends along the entire rim ofthe wheel. To hold the media pack in place it is advantageous to let theperipheral element extend along the entire rim. However, it could alsobe built up by segments, for easier handling, and in that case there maybe small gaps between the different sections when mounting the wheel.That would not affect the ability to keep the media pack secured.

In one embodiment, the tubular hub comprises either an integral cylinderor two or more cylinder segments, which together form a cylinder. Forsmaller sizes of wheels it is advantageous to manufacture the hub as anintegral cylinder and in that way be spared from an extra assembly step.For larger sizes of wheels it may be difficult to manufacture the hub inone piece, at least at reasonable costs. In that case a cylinder puttogether by cylinder parts is most advantageous.

Preferably, the cylinder or the cylinder segments comprises/compriseextruded profiles. Some advantages with an extruded profile are thesurface finish, and the possibility to produce complex cross-sections,like the cylinder or cylinder sections of this thermal wheel hub.

In one embodiment, the cylinder segments are attached to each other bymeans of connection parts inserted into holding means of the hub. Thisis an efficient way of assembling the cylinder parts to a finishedcylinder. It is also effective to use the same connection parts both forthe cylinder assembling and for the connection of the spokes to the hub,but it is of course possible to use a connection part with one shape forthe assembling, and a connection part with another shape for the spokes.One example would be to use a rectangular connection part for theassembly of the hub, and a circular connection part for the fastening ofthe spokes.

In another embodiment, the connection parts are substantiallyrectangular in cross section. If the connection means is rectangular itis advantageous to use a rectangular connection part. If the connectionmeans has another shape, the connection part should be correspondinglyshaped. It would also be possible to use two differently shapedconnection parts, if the connection means and the holding means are ofdifferent shapes.

In one embodiment, the connection part comprises a recess in which anelongate elevation comprised by the holding means of two adjacentcylinder segments is fittable. The recess together with the elevation iswhat holds two cylinder segments together allowing for efficientassembly of the hub.

Preferably, the spokes are connectable to the connection parts byfastening means. Instead of making the spoke and the connection part asone integral piece it is advantageous to produce them as two separatepieces. The spoke may be an extruded profile and the connection part apiece that may be used both with the spoke and when assembling thecylinder parts.

In another embodiment, a cover plate is connectable to the hub byfastening means which are engageable with circular connection means onthe inside of the hub. A cover plate is advantageous to mount on thewheel, forcing all air to pass through the heat and/or mass transferringmedia pack instead of going through the hub. The fastening is done withself-tapping screws, and the circular connection means are provided inthe extruded hub profile. The cover plate also works as bearing seat fora shaft.

Preferably, radial grooves are comprised in the media pack from the hubto the periphery of the wheel, into which the spokes are placed. Byplacing the spokes into the grooves the surface of the wheel gets even,with no protruding parts.

In one embodiment, before arranging the spokes in the grooves, they arefilled with glue to fix the spoke. Further, the glue holds together thecut up layers of the media pack and contributes to hold the wheeltogether.

In a second aspect of the disclosure, a kit for forming a thermal wheelis provided. The kit comprises a hub and spokes which are connectable tothe hub. The hub and the spokes form together a structure for supportinga media pack, which is preferably enclosed by a peripheral member.

In a third aspect of the disclosure, there is provided an apparatusadapted for heat and/or mass transfer and comprising at least one rotarythermal wheel.

In a fourth aspect of the disclosure, a method of producing a rotarythermal wheel is provided. The method comprises the step of connectingthe spokes to the hub by means of connection parts inserted intoconnection means. An advantage of this method for assembling the wheelis that no welding is necessary, which may cause crack formations, shapechanges and which produce harmful gases.

In a fifth aspect of the disclosure a use of a hub and radial spokes isprovided. The use comprises the hub with radial spokes connected theretofor supporting a media pack which is preferably enclosed by a peripheralmember.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure will be described in the following;references being made to the appended diagrammatical drawings whichillustrate non-limiting examples of how the inventive concept can bereduced into practice.

FIG. 1 is an end view of an assembled thermal wheel.

FIG. 2 is a cross section of a hub of the thermal wheel.

FIG. 3 corresponds to FIG. 2 and shows the hub with a spoke attachedthereto.

FIG. 4 shows on a larger scale a portion of a segment-built hub with aconnection part inserted into a holding means of the hub.

FIG. 5 shows the hub of FIG. 4 held together by connection parts.

FIG. 6 is a perspective view of a hub of a thermal wheel held togetherby connection parts and with an illustrative spoke mounted.

FIG. 7 shows on a larger scale the spoke of FIG. 6 connected to the hub.

FIG. 8 shows the connected spoke of FIG. 7 from a different angle.

FIG. 9 is an end view of another assembled thermal wheel.

FIG. 10 is a cross section of a spoke.

FIG. 11 is a cross section of a connection part.

FIG. 12 is a cross section of an integral hub of a thermal wheel.

FIG. 13 is a cross section of the hub of FIG. 12 with spokes attached.

FIG. 14 is a perspective view of a hub of two segments of a thermalwheel with a cover plate and a spoke.

FIG. 15 shows a schematic cross section of the cover plate in FIG. 14 ona larger scale, taken along section line XV-XV.

FIG. 16 is an end view of an assembled thermal wheel.

FIG. 17 is an end view of a segment-built hub of a thermal wheel.

FIG. 18 is an end view of another segment-built hub of a thermal wheelwith spokes attached thereto.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, certain embodiments will be described more fully withreference to the accompanying drawings. The disclosure may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided by way of example so that this disclosure will be thorough andcomplete, and will fully convey the scope of the disclosure to thoseskilled in the art.

In FIG. 1 a rotary thermal wheel 500 according to one embodiment of thepresent disclosure is shown. The thermal wheel 500 has an innercylindrical hub 100, a media pack 300 wound onto the hub 100, aperipheral member 400, and four rigid spokes 200 attached to the hub 100by connection parts 210 and to the peripheral member 400 by a screw 260.The rigid spokes 200 provide the wheel with stability. The media pack300 is built up by alternately flat and corrugated metal sheets, andforms the heat and/or mass transferring part of the thermal wheel 500.The metal sheets may be coated with e.g. an epoxy lacquer, or othercoatings. The peripheral member 400 encloses the outer periphery of thethermal wheel 500 and supports the media pack 300. Preferably, theperipheral member 400 consists of a one piece metal strip, but it mayalso be divided into several strips, dependent of the diameter of thethermal wheel 500. Easier handling is accomplished with severalperipheral member 400 parts when it comes to a larger wheel diameter.

In FIG. 2, the hub 100 of the thermal wheel 500 is shown separately. Thetubular hub 100 is substantially circular with a substantially evenouter surface 110, and its inside 120 is provided with substantiallyrectangular connection means 130 and substantially circular connectionmeans 140. As is shown, the hub 100 has four substantially rectangularconnection means 130, and four substantially round connection means 140.The rectangular 130 and the round 140 connection means are equidistantlyand alternately arranged over the inner surface 120 of the hub 100.

Each rectangular connection means 130 is built up by two wall elements135, 136, 135′, 136′. The wall element 135′, 136′ of each connectionmeans 130 has one straight portion 135′ closest to the inner surface 120of the hub 100, the straight portion 135′ extending generallyperpendicularly thereto, and one holding portion 136′, closer to thecenter of the hub 100, wherein the holding portion 136′ extendsperpendicularly to the straight portion 135′, i.e. generally parallelwith the inner surface 120. Together, the straight portion 135′ and theholding portion 136′ provide a hook shaped part.

More specifically, an inner surface 137′ of the right wall element 135′,136′, i.e. the surface on the inside of the connection means 130,extends into the inner of the hub 100 with a certain angle and itextends for a certain length, providing an inner side of the straightportion 135′. The inner surface 137′ of the wall element 135′, 136′connects to a surface 131′ which extends transversally against the innersurface 137′ and has a certain length. Together, the two surfaces 137′,131′ form the holding portion 136′ of the wall element 135′, 136′ makingup a detaining part of the connection mean 130.

The surface 131′ connects to another surface 132′, which extendstransversely with respect to the surface 131′. A surface 138′ connectsto this surface 132′ and extends in a circumferential direction withrespect to the center of the hub 100. Moreover, the surface 138′ isslightly curved so as to receive a flange provided on the inside of acover plate 600, which will be further described in the following. Thesurface 138′ is connected to a surface 133′, and the angle between thesetwo surfaces 138′, 133′ is slightly larger than 90 degrees. The surface133′ forms an outer surface of the holding portion 136′ and it extendsto the level of a corner formed by the connection between the surfaces137′, 131′. Finally, a surface 134′ is parallel with the surface 137′ ofthe straight portion 135′, and continues to the inner surface 120 of thehub 100. The left wall element 135, 136 of the rectangular connectionmean 130 is mirrored compared to the right one 135′, 136′ and are markedwith the numerals 131-138.

A shallow groove 139 is provided in the inner surface 120 of the hub100, centrally between the right wall elements 135′, 136′ and the leftwall elements 135, 136. The shallow groove 139 extends approximately athird of the distance between the wall elements 135′, 136′ and the wallelements 135, 136. The dotted part of the rectangular connection means130 to the left in the figure is where the connection part 210,mentioned in conjunction with FIG. 1 and to be explained later, is to beinserted.

The circular connection means 140 each has a bridge portion 141 and acircular portion 142. The bridge portion 141 connects the circularportion 142 to the inner surface 120 of the hub 100. The circularportion 142 comprises about three quarters of a circle, which is open ina direction towards the center of the hub 100. The circular connectionmeans 140 are arranged to function as screw pockets for attaching acover plate 600 (to be explained in conjunction with FIG. 14-16) to thehub 100 by the fastening means 260. The dotted part of the connectionmeans 140 in the left of the figure is where the fastening means 260 isto be inserted.

The wall elements providing the rectangular connection means 130 andcircular connection means 140 extend along the entire length of the hubcylinder 100.

FIG. 3 shows a connection part 210, connecting a spoke 200 and the hub100. The connection part 210 has a shape of a rectangular cuboid whichis limited by six surfaces, wherein one large surface 240 faces aninternal of the hub 100. An opposite surface 220 thereof faces the innersurface 120 of the hub 100 and is provided with an elongate recess 280,the function of which will be explained later. The large surfaces 240and 220 are joined by side surfaces 230, 230′, which side surfaces runparallel to a rotational axis of the hub 100. Finally, the rectangularcuboid is provided with two end surfaces, wherein only one end surface,facing upwards in FIG. 3, is shown. Moreover, the rectangular cuboidcomprised in the connection part 210 is provided with a through opening(not shown) extending between the large surface 220 and the largesurface 240.

During use, the connection part 210 is inserted into the space limitedby the inner surface 120 of the hub 100, the surface 137, 137′ and thesurfaces 131, 131′. In other words, the connection part 210 will be heldin place due to engagement between the inner surface 120 of the hub 100and the large surface 220 of the connection part, the side surfaces 230,230′ of the connection part 210 and the surfaces 137, 137′ of therectangular connection means 130 and the surfaces 131, 131′ of therectangular connection means 130 and the large surface 240 of theconnection part 210, respectively. This results in a complementaryshaped connection. In other words, the other shape of the connectionpart 210 matches the recess defined by the surfaces 120, 131, 131′, 137and 137′ as illustrated in FIG. 2.

The rigid spoke 200 is connected to the connection part 210 by aself-tapping screw 260, extending through the opening and engaging apart of the large surface 240 and a recess 270 running in an axialdirection of the spoke 200. An end of the spoke 200 may be fitted intothe elongate recess 280, which fit will give a more reliable connectionbetween the connection part 210 and the spoke 200. In other embodimentsof the disclosure, the spoke 200 may be fastened to the connection part210 by a screw 260 extending into a threaded opening of the connectionpart 210 through an opening provided in the spoke 200, i.e. such thatone side of the spoke 200 will engage the end surface of the connectionpart 210.

The spoke 200 comprises a long and narrow rectangular cuboid, havingalmost the same length as the radius of the thermal wheel 500 (to bemore specific, the length of the spoke 200 is the radius of the thermalwheel minus the radius of the hub 100).

In FIG. 4, the connection between two cylinder segments 150 c, 150 d ofanother embodiment is shown. In this embodiment, the hub 170 is built upby four cylinder segments 150 c, 150 d, 150 e, 150 f (to be furtherexplained in conjunction with FIG. 5), which are joined to one anotherby holding means 290 resembling the design of the rectangular connectionmeans 130 and the connection part 210. The few differences will beelaborated on below:

As mentioned, the holding means 290 resembles the rectangular connectionmeans 130—in fact, all components are similar, except for the provisionof an elongate elevation 293, 293′, which runs parallel to alongitudinal axis of the hub 170 instead of the elongate recess 280 ofthe connection means 130. Between the elongate elevations 293, 293′ isthe splice between the cylinder segments 150 c-150 d.

In use, two cylinder segments 150 c, 150 d are placed in the desiredposition with regard to one another, and a connection part 210 isinserted in the space limited by the inner surface 120 of the hub 170,the surface 137, 137′ and the surfaces 131, 131′. In other words, theconnection part 210 will be held in place due to engagement between theinner surface 120 of the hub 170 and the large surface 220 of theconnection part 210, the side surfaces 230, 230′ of the connection part210 and the surfaces 137, 137′ of the rectangular connection means 130and the surfaces 131, 131′ of the rectangular connection means 130 andthe large surface 240 of the connection part 210, respectively.Furthermore, due to cooperation between the elongate elevations 293,293′ and the elongate recess 280 of the connection part 210, thecylinder segments 150 c, 150 d will be locked to one another.

In FIG. 5, a complete hub 170 is shown. The hub 170 is built up by fourcylinder segments 150 c, 150 d, 150 e, 150 f joined by eight connectionparts 210 as described in connection with FIG. 4, four from one end ofthe hub 170 and four from the other. It is, of course, also possible tojoin the cylinder segments by only four connection parts 210; if onlyfour connection parts are used, they should preferably have a lengthcorresponding to the length of the hub 170.

A hub 170 with one rigid spoke 200 attached is shown in FIG. 6. Thespoke 200 is attached by a connection part 210, as described inconnection with FIG. 3. A groove is cut out in the hub 170 with the samedimensions as the spoke 200, so as the connection part 210 can becompletely inserted into the connection means 130 such that the surface294 of the spoke 200 is at the same level as the surface 295 of the hub170 (This is also shown in FIG. 14).

In FIGS. 7 and 8, two details of FIG. 6 are shown on a larger scale. Twocylinder segments 150 c, 150 d are attached to one another by means of aconnection part 210 inserted into the holding mean 290. The rigid spoke200 is attached to the connection part 210 by means of a screw 260, andthe connection part 210 is inserted into a rectangular connection means130.

With reference to FIG. 9 a complete thermal wheel 500 is shown. Thewheel 500 has an inner cylindrical hub 150, a media pack 300 winded ontothe hub 150, a peripheral member 400 and six rigid spokes 200 attachedto the hub 150 by connection parts 210, and to the peripheral membere.g. by screws 260. The hub 150 has two cylinder parts 150 a, 150 battached to one another by connection parts 210. The media pack 300comprises alternately flat and folded metal sheets, winded onto thecylindrical hub 150. The media pack 300 forms the heat and/or masstransferring part of the thermal wheel 500. The peripheral member 400limits an outer periphery of the thermal wheel and encloses the mediapack 300.

Grooves 900 are cut in the media pack 300 along a line extending fromthe hub 150 to the peripheral element 400 in which the spokes 200 areplaced. Glue is, as an option, provided in the grooves 900 in the mediapack 300 to fix the spokes 200. The thermal wheel 500 structure issymmetrical and even though it is shown from one side in the figure, theother side looks just alike.

With reference to FIG. 10, a cross section of a spoke 200 is shown. Thiscross section is mainly rectangular with two parallel long sides 201 andtwo parallel short sides 202. The spoke 200 is mirror symmetrical withreference to a central axis parallel with the long sides 201. In one ofthe short sides 202, the one which faces the media pack 300 when mountedon the thermal wheel 500, a groove 270 is provided. The groove 270 has asurface 203 which begins close to a corner where the long surface 201meets the short surface 202, and it stretches towards the central axisof the spoke 200 with a slope of approximately 45 degrees in relation tothe short side 202. A surface 203′ is mirror-symmetrical to the surface203 with respect to the central axis parallel with the long sides 201. Asecond surface 204 of the groove 270 is circularly shaped, approximatelythree quarters of a circle and connects the two surfaces 203 and 203′.The spoke 200 may have this cross section appearance along its wholelength, or it may have this appearance in the end portions and e.g. besolid in a middle portion.

The space enclosed by the surface 204 is configured to receive afastening means 260 which attaches a connection part 210 to one end ofthe spoke 200 and a fastening means 260 which connects the spoke 200 tothe peripheral member 400 in an opposite end of the spoke 200. The spaceenclosed by the surface 204 is prepared for a self-tapping screw. Thesloped opening provided by the surfaces 203, 203′ is optionally filledwith glue which fixes the spoke 200 to the media pack 300 when thethermal wheel 500 is mounted.

With reference to FIG. 11, a cross section of a connection part 210 isshown. The connection part 210 is mainly rectangular, with one even longside 701 and two short sides 702. Parallel with the even long side 701is a long side comprising a recess 710. The recess 710 has a surface 703which is parallel with the long surface 701 and which has the same widthas the surface 202 of the spoke 200. The surface 703 is providedcentrally on the long side 701. The recess 710 further comprises twoshort sides 704 parallel with the short sides 702 of the connection part210. At each side of the recess 710 is a surface 705, 705′. The surfaces705, 705′ are each provided with two small protrusions 706. The recess710 has two purposes. The first is to engage with the spoke 200 when thetwo are mounted to each other. The second purpose is to engage with theelongate elevations 293, 293′ of the holding means 290, 290′ to ensurethat two adjacent cylinder segments are kept together.

FIG. 12 shows a cross section of a hub 100 of a thermal wheel 500. Theview is similar to the one of FIG. 2, but in FIG. 12 a dashed lineshowing the purpose of the surface 138, 138′ is plotted, i.e. a flangeof a cover plate 600 are to be arranged along the dashed line to keepthe cover plate 600 in place.

With reference to FIG. 13, a cross section of a hub 100 of a thermalwheel 500 is shown. The view is similar to the one of FIG. 3, but inFIG. 13 rigid spokes 200 connected to connection parts 210 are attachedto all four rectangular connection means 130.

FIGS. 14-16 illustrate a hub 150 having two cylinder segments 150 a, 150b with a cover plate 600, a cover plate 600 in cross section and a coverplate 600 mounted on a thermal wheel 500, respectively. The cover plate600 is circularly shaped with an even top surface 601, which has adiameter slightly larger than the diameter of the hub 150 which it willfit on. Perpendicular to the surface 601 is a peripheral surface 602 ofthe cover plate 600 and perpendicular to the surface 602 and parallelwith the surface 601 is a surface 603. The width of the surface 603corresponds to the height of the rectangular connection mean 130.Perpendicular to the surface 603 and parallel with the surface 602 is asurface 604, perpendicular to the surface 604 and parallel with thesurfaces 601, 603 is a surface 605. In the center of the cover plate 600there is provided a circular through hole or opening with the samediameter as a driving shaft 910 of the thermal wheel 500. A bearing isalso arranged in the center of the cover plate 600.

The surfaces 604 and 605 shown in FIG. 15 provide a flange to the coverplate 600 which is fitted into the hub 150. The cover plate 600 is heldin place by the close fit to the rectangular connection means 130 and byfastening means 260 fitted into the circular connection means 140. Thedashed line in FIG. 12 shows where the surface 604 lays against surface138, 138′ of the rectangular connection means 130. The cover plate 600provides a lid to the thermal wheel hub which can be either of the hubs100, 150, 170, 800 in order that the air cannot go through the hub 100,150, 170, 800 but instead is forced through the media pack 300. Theslightly larger diameter of the cover plate 600 surface 601 compared tothe hub 150 diameter provides an edge which keeps the first round of themedia pack 300 still when winded onto the hub 150.

Remaining hubs 100, 170, 800 are provided with corresponding coverplates 600 as well, in order not to let air pass through the hubs 100,170, 800. The cover plate 600 has in each case a diameter slightlylarger than the diameter of the current hub 100, 170, 800. Further,applicable to larger hubs 150, 170, 800 comprising several cylinderparts 150 a-b, 150 c-f, 150 g-i, the cover plate 600 keeps the cylindersegments 150 a-b, 150 c-f, 150 g-i together, along with the holdingmeans 290.

In FIG. 14 the spoke 200 is connected to the hub 150 by a connectionpart 210 and fully inserted into the connection recess 130, therebyready to receive the cover plate 600. The hub 150 is provided with cutouts 610 in the outer surface 110 of the hub 150 at the same level asevery rectangular connection means 130. The spoke 200 is fitted into therecess 610 when the thermal wheel 500 is put together. The top surfaceof the connection part 210 is thus on the same level as the end surfaceof the hub 150.

With reference to FIG. 17 a larger segment-built hub 170 of a thermalwheel 500 is shown. The hub 170 is built up by four cylinder segments150 c, 150 d, 150 e, 150 f, connected to each other by means ofconnection parts 210 inserted into the holding means 290. Eight rigidspokes 200 are connected to the hub 170 by means of connection parts 210inserted into the rectangular connection means 130.

In FIG. 18 a hub 800 comprising three segments 150 g, 150 h, 150 i isshown. As in the previously described embodiments, the joints (152 a,152 b, 152 c) of these segments 150 g, 150 h, 150 i are connected bymeans of rectangular connection parts 210. Like the previously describedhubs, this hub 800 comprises circular connection means 140 andrectangular connection means 130. Rigid spokes 200 are attached by meansof rectangular connection parts 210 inserted into the rectangularconnection means 130.

In one embodiment the complementary shaped connection of the spokes maybe a wedged shaped connection or a wedge connection. In this embodimentthe connection part fastened to one end of the spoke is wedged into therectangular connection means of the hub.

An advantage of the hub 100, 150, 170, 800 of the embodiments describedherein is the standardized production. The connection part 210 is usedboth when assembling the cylinder segments 150 a-b, 150 c-f, 150 g-i toform a hub 150, 170, 800 with a larger diameter, and when attaching thespokes 200 to the hub 100, 150, 170, 800. Furthermore, the connectionpart 210 has the same size irrespective of the diameter of the hub 100,150, 170, 800 to be mounted. It is of course possible to havedifferently shaped connection parts 210 to connect the hub segments 150a-b, 150 c-f, 150 g-i with one another and to connect the spokes 200 tothe hub 100, 150, 170, 800, but it is not necessary.

The wheels 500 described in the embodiments above preferably include aperipheral member 400, but it would be possible to manufacture a wheel500 without this member 400, e.g. by struts connecting the spokes 200straight through the media pack 300. The thermal wheels 500 described inthe embodiments have media packs 300 winded onto the hub 100, 150, 170,800, but this is not necessary. The media pack 300 may be attached tothe hub 100, 150, 170, 800 in sections, and in that case it is notnecessary for the connection means 130, 140 to be placed on the insideof the hub 100, 150, 170, 800 since this design does not demand an evenouter surface of the hub 100, 150, 170, 800.

The thermal wheels 500 described herein are all provided with anefficient supporting structure for keeping together the media pack 300.This supporting structure is formed by the hub 100, 150, 170, 800, thespokes 200 and the related connection means 130, and preferably theperipheral member 400.

The shape and number of the rectangular connection means 130, circularconnection means 140, or the holding means 290 may vary depending on thesize of the thermal wheel 500 or by other factors.

Advantages of some embodiments described herein are that the media packis not affected during the assembly of the heat transfer wheel. There isno weld seam which prohibits airflow. Also, if a media pack comprisingalternating flat and corrugated layers is exposed to welding thecorrugated layers are affected and may collapse, leading to a chainreaction of collapsed layers, which ultimately leads to a collapsedmedia pack, i.e. a collapsed heat transfer wheel. This scenario iseffectively eliminated by the structure described herein.

A further advantage of some embodiments is that a complementary shapedconnection is more stable than e.g. a weld seam when the heat transferwheel is in operation. The wheel in operation is constantly affected byan alternating air pressure: an upper section is affected by an airpressure in one direction and a lower section by an air pressure in anopposite direction. Since the wheel rotates every specific area of thewheel will be affected by two different air pressure, with oppositedirections, during each revolution of the wheel. A welded wheel is moreprone to break during operation than a wheel comprising complementaryshaped connections.

In an additional aspect, a hub for a thermal wheel is provided. The hubcomprises two or more cylinder segments having holding means. Adjacentsegments are connected to each another by means of matching,correspondingly shaped connection parts inserted into the holding means.These connections are complementary shaped connections. The cylindersegments preferably comprise extruded profiles. The holding meanscomprise recesses formed on an inside of the hub. Preferably, theholding means are of substantially rectangular shape and equidistantlyarranged around the inside of the hub.

It is appreciated that the inventive concept is not limited to theembodiments described above, and many modifications are feasible withinthe scope of the disclosure set forth in the appended claims. Forinstance the number of spokes, the number of cylinder segments and thenumber of sections of a finished wheel may vary. Also the number ofcircular connection means may vary, in particular with the diameter ofthe wheel. The shapes of the connection parts and correspondingconnection means may also vary. Some examples of shapes are for instancesquare, round, oval or rectangular.

The connection means and holding means may have the same shape, but mayalso be of different shapes. For example it is possible to userectangular connection means and circularly shaped holding means. Thecomplementary shaped connection could comprise small connection parts,one part inserted into the hub from each side, or it could comprise onelong connection part. The peripheral member may be formed as one longstrip, or several shorter strips. The spokes as well as the connectionparts may have the described cross sections, but they could also haveother cross sections.

1. A rotary thermal wheel for heat transfer, mass transfer or a combination of heat and mass transfer, said wheel comprising: a hub; a number of radial spokes connected to the hub; and a heat or mass transferring media pack in a space defined by the hub and the spokes; wherein the hub comprises a tubular element provided with a hub connection; and wherein the spokes are connected to the hub by connection parts matching the hub connection that is correspondingly shaped, a spoke connection of the spokes being complementary shaped.
 2. The thermal wheel according to claim 1, wherein the hub connection includes recesses formed on an inside of the hub, and wherein the connection recesses are of a substantially rectangular shape.
 3. (canceled)
 4. The thermal wheel according to claim 2, wherein the rectangular connection recesses comprise wall elements so as to provide grooves.
 5. The thermal wheel according to claim 1, wherein the spokes are attachable to the hub by the connection parts fastened to one end of the spoke and inserted into the hub connection including a rectangular shape.
 6. The thermal wheel according to claim 1, wherein the hub connection is equidistantly arranged around the inside of the hub.
 7. The thermal wheel according to claim 1, further comprising a peripheral member extending around the outer periphery of the thermal wheel and being connected to the spokes by a fastening member, said peripheral member enclosing the media pack.
 8. The thermal wheel according to claim 1, wherein the spokes extend radially from the hub to the peripheral member.
 9. The thermal wheel according to claim 1, wherein the peripheral member extends along the entire rim of the wheel.
 10. The thermal wheel according to claim 1, wherein the tubular hub includes at least one of an integral cylinder or two or more cylinder segments which together form a cylinder, and wherein at least one of the cylinder or cylinder segments include extruded profiles.
 11. (canceled)
 12. The thermal wheel according to claim 1, wherein the cylinder segments are attached to each other by connection parts inserted into a holding member of the hub.
 13. The thermal wheel according to claim 12, wherein the connection parts are substantially rectangular in cross section.
 14. The thermal wheel according to claim 12, wherein at least one of the connection parts comprises a recess in which an elongate elevation including the holding member of two adjacent cylinder segments is fittable.
 15. The thermal wheel according to claim 12, wherein the spokes are connectable to the connection parts by a fastening member.
 16. The thermal wheel according to claim 1, wherein a cover plate is connectable to the hub by a fastening member that is engageable with a circular connection on the inside of the hub.
 17. The thermal wheel according to claim 1, wherein radial grooves are provided in the media pack, into which grooves the spokes are to be placed.
 18. The thermal wheel according to claim 1, wherein glue is provided in the radial grooves to fix said spokes.
 19. A rotary thermal wheel for heat transfer, mass transfer or a combination of heat and mass transfer, said wheel comprising: a cylindrical hub which includes two or more cylinder segments; a number of radial spokes connected to the cylinder-segment hub; and a heat or mass transferring media pack in a space defined by the cylinder-segment hub and the spokes; wherein the cylinder-segment hub comprises a hub connection; and wherein the spokes are connected to the cylinder-segment hub by connection parts matching the hub connection that is correspondingly shaped, a spoke connection of the spokes being complementary shaped.
 20. A kit for forming a thermal wheel, comprising: a hub; and spokes connectable to the hub, thereby forming a structure which supports a media pack enclosed by a peripheral member.
 21. The thermal wheel according to claim 1, wherein the thermal wheel is configured as an apparatus for heat transfer, mass transfer or a combination of heat and mass transfer.
 22. The thermal wheel according to claim 1, wherein the spokes are connected to the hub by the connection parts being inserted into the hub connection.
 23. (canceled) 